Hostname: page-component-5c6d5d7d68-7tdvq Total loading time: 0 Render date: 2024-08-23T01:18:28.405Z Has data issue: false hasContentIssue false
  • English
  • Français

Inertial impaction of heavy molecules

Published online by Cambridge University Press:  20 April 2006

J. Fernández De La Mora ,
B. L. Halpern  and
J. A. Wilson
J. Fernández De La Mora
Affiliation:
Departments of Mechanical and of Chemical Engineering, Yale University, New Haven, Connecticut 06520
B. L. Halpern
Affiliation:
Departments of Mechanical and of Chemical Engineering, Yale University, New Haven, Connecticut 06520
J. A. Wilson
Affiliation:
Departments of Mechanical and of Chemical Engineering, Yale University, New Haven, Connecticut 06520
Get access Rights & Permissions [Opens in a new window]

Abstract

The transition from diffusion-dominated to inertia-dominated behaviour in the transport of condensable heavy molecules carried in a continuum subsonic He jet that impinges on a solid surface is studied experimentally. The Stokes number S, or ratio between the heavy-molecule relaxation time and the fluid-dynamic time, is varied in the interval 0 [lsim ] S [lsim ] 1 by changing the jet Mach number at a constant value of the Reynolds number. Although the heavy species departs considerably from equilibrium at all but the smallest values of S, the helium jet is always near equilibrium conditions. At values of S of order unity the observed rate of deposition at the stagnation point asymptotes to a value some six times greater than in the diffusion region (where S → 0), implying that the process is governed by the large inertia of the heavy species, very much like in aerosol impactors. As a result, it is argued that the concept of pressure diffusion is unsuitable to explain the observed behaviour. An approximate theoretical description of the transport process is given for the region S [Lt ] 1 where the kinetic problem is amenable to a hydrodynamic treatment. Finally, the analogy with the inertia-dominated behaviour of aerosols is used to assess the relative merits of various aerodynamics schemes aiming at separating isotopes.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 149 , December 1984 , pp. 217 - 233
Copyright
© 1984 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Becker, E. W. 1978 In Uranium Enrichment (ed. S. Villani), p. 322. Springer.
Becker, E. W., Bier, W., Bley, P., Ehrfeld, W., Shubert, K. & Seidel, D. 1982 Development and technical implementation of the separation nozzle process for enrichment of U-235. Kernforschungszentrum Karlsruhe, KFK 3310.
Becker, E. W., Bley, P., Ehrfeld, U. & Ehrfeld, W. 1977 The separation nozzle—an aerodynamic device for large-scale enrichment of uranium-235. In Rarefied Gas Dynamics (ed. J. L. Potter), pp. 3–16. AIAA Prog. Astronautics Aeronautics, vol. 51.
Bley, P. & Ehrfeld, W. 1981 Molecular dynamics of disparate-mass-mixtures in opposed jets. In Rarefied Gas Dynamics (ed. S. S. Fisher), pp. 557–589. AIAA Prog. Astronautics Aeronautics, vol. 74.
Chapman, S. & Cowling, T. G. 1970 The Mathematical Theory of Non-uniform Gases. Cambridge University Press.
Cole, J. D. 1968 Perturbation Methods in Applied Mathematics. Blaisdel.
Farthing, W. E. 1983 Aerosol Sci. Tech. 2, 242.
Fernández de la Mora, J. 1982 Phys. Rev. A 25, 1108–1122.
Fernández de la Mora, J. 1984 The aerosol—heavy molecule analogy and the dispersion of sound by gas mixtures of disparate masses. J. Phys. Chem. (in press).Google Scholar
Fernández de la Mora, J. & Mercer, J. M. 1982 Phys. Rev. A 25. 2178–2187.
Fernández de la Mora, J., Mercer, J. M., Rosner, D. E. & Fenn, J. B. 1981 Simplified kinetic treatment of heavy molecule velocity persistence effects: application to species separation. In Rarefied Gas Dynamics (ed. S. S. Fisher), pp. 617–626. AIAA Prog. Astronautics Aeronautics, vol. 74.
Fernández de la Mora, J. & Rosner, D. E. 1981 Physicochem. Hydrodyn. 2, 1–21.
Fernández de la Mora, J. & Rosner, D. E. 1982 J. Fluid Mech. 125, 379–395.
Friedlander, S. K. 1977 Smoke, Dust and Haze. Wiley.
Fuchs, N. A. 1964 The Mechanics of Aerosols. Pergamon.
Hering, S. V., Friedlander, S. K., Collins, J. J. & Richards, W. 1979 Environ. Sci. Tech. 13, 184–188.
Israel, R. & Rosner, D. E. 1983 Aerosol Sci. Tech. 2, 45–51.
Marple, V. A. & Willeke, K. 1979 Inertial impactors. In Aerosol Measurement (ed. D. A. Lundgren et al.), pp. 90–106. University Press of Florida, Gainesville.
Pavlik, R. E. & Willeke, K. 1978 Am. Indust. Hyg. Assn J. 39, 952.
Ramshaw, J. D. 1979 Phys. Fluids 22, 1595–1601.
Ramshaw, J. D. 1981 Phys. Fluids 24, 1210–1211.
Reis, V. H. & Fenn, J. B. 1963 J. Chem. Phys. 39, 3240.
Schissel, P. O. & Trulson, O. C. 1965 J. Chem. Phys. 43, 737–743.
Schlichting, H. 1968 Boundary Layer Theory. McGraw-Hill.
Shapiro, A. H. 1953 The Dynamics and Thermodynamics of Compressible Fluid Flow. Ronald.
Tolfo, F. 1975 The production, dispersion and coagulation of condensation aerosols in the wake of a filament vapor source. Ph.D. thesis, Yale University.
Willeke, K. 1980 Centrifugal particle classification. Environ. Sci. Tech. 14, 461–465.Google Scholar
Willeke, K. & Pavlik, R. E. 1978 Environ. Sci. Tech. 12, 563.
Willeke, K. & Pavlik, R. E. 1979 J. Aerosol Sci. 10, 1.